Nexrad Limitations; Fis-B Nexrad - Garmin GTN 725 Pilot's Manual

12.6.2
Foreword
WSR-88D weather surveillance radar or NEXRAD (NEXt generation RADar) is
Getting
a Doppler radar system that has greatly improved the detection of meteorological
Started
events such as thunderstorms, tornadoes, and hurricanes. An extensive network
Audio &
of NEXRAD stations provides almost complete radar coverage of the continental
Xpdr Ctrl
United States, Alaska, and Hawaii. The unobstructed range of each NEXRAD is
Com/Nav
124 nautical miles.
12.6.2.1
FPL
There are possible abnormalities regarding displayed NEXRAD images. Some,
Direct-To
but not all, causes of abnormal displayed information include:
• Ground Clutter
Proc
• Strobes and spurious radar data
Charts
• Sun strobes, when the radar antenna points directly at the sun
• Military aircraft deploy metallic dust which can cause alterations in radar
Wpt Info
scans
Map
• Interference from buildings or mountains, which may cause shadows
• Scheduled maintenance may put a radar off-line
Traffic
12.6.2.2
Terrain
Certain limitations exist regarding the NEXRAD radar displays. Some, but
not all, are listed for the user' s awareness:
Weather
• NEXRAD base reflectivity does not provide sufficient information to
determine cloud layers or precipitation characteristics (hail vs. rain, etc).
Nearest
• NEXRAD base reflectivity is sampled at the minimum antenna elevation
Services/
Music
angle. An individual NEXRAD site cannot depict high altitude storms at
close ranges, and has no information about storms directly over the site.
Utilities
• The resolution of displayed Regional NEXRAD data is approximately
System two kilometers and the resolution of displayed CONUS NEXRAD data is
approximately 10 kilometers. Therefore, when zoomed in on the display,
Messages
each square block is two kilometers (1.08 NM) or 10 kilometers (5.4 NM)
on a side. The intensity level reflected by the square will be the highest
Symbols
level sampled within the area covered by each block.
Appendix
12-74
Index

FIS-B NEXRAD

NEXRAD Abnormalities

NEXRAD Limitations

Garmin GTN 725/750 Pilot's Guide 190-01007-03 Rev. D